1. Field of the Invention
The subject disclosure relates generally to a system for removing residual or accumulated concrete from interior surfaces of a concrete mixing drum, and more particularly, to a system for releasing or dislodging concrete accumulated on or about the helical flights of a concrete mixing drum.
2. Background of the Related Art
Ready-mix concrete trucks, such as the truck illustrated in FIG. 1, have a rotatable drum for holding a quantity of ready-mix concrete. The drum typically includes several raised helical ribs or flights extending around its interior surfaces. These ribs act to mix the concrete when the drum is rotated in one direction, and when the drum is rotated in the opposite direction, the ribs lift the concrete to an elevated opening, either at the front or rear of the drum, through which the concrete is discharged from the drum.
Over the course of operation, concrete has been found to accumulate on the surfaces in the drum and the flight, particularly on the surfaces of the flight facing away from the open end of the drum. This concrete, if left in place to cure and harden, will decrease the effectiveness of the flights for both mixing and lifting the concrete, and adds weight to the truck. Furthermore, if allowed to accumulate, the concrete will also lessen the capacity of the drum. Therefore, it is common practice, at the end of each day, or more often, to wash the interior of the drum. However, the washing typically requires as much as 300 gallons of water, and still has been found to be ineffective at removing the accumulated concrete from the surfaces of the ribs facing opposite the open end of the drum, especially if the concrete is allowed to cure and harden.
Various apparatus and methods for removing concrete and cleaning concrete mixing drums have been used in the past, such as, for example, a hand held probe for spraying a set retarding agent against the residual concrete on the inner surface of the drum, a vibration impact device applied against the exterior of the concrete mixing drum for loosening and dislodging the accumulated concrete. These have shortcomings such as the ineffectiveness of the retarding agents under a variety of environmental conditions such as elevated temperatures and for removing concrete that has largely or mostly cured. Limitations of using devices which extend into a drum include unwieldiness, particularly when using pressurized fluids. Also, the fluid must be disposed of thereafter and it is unsafe to rotate the drum when devices are extended therein, particularly hand held devices. Shortcomings of vibrational methods of cleaning concrete mixing drums include the noise generated by the vibrating devices and the time required.
Ultimately, it has been found that the known cleaning apparatus and methods often still leave sufficient residual concrete on the interior surfaces of the drum so as to require periodic manual cleaning. This typically involves a worker entering the drum, and using a water hose and hand or power tools as required, loosening the concrete from the drum surfaces and washing the concrete pieces to the bottom of the drum. When all the concrete is loose, the worker exits the drum, and the drum is rotated so as to discharge the cleaning water and concrete pieces from the drum.
It should be readily apparent that manual cleaning of a mixing drum is tedious, and furthermore, poses significant risk of injury to the worker. The worker may be injured while entering or exiting the drum, which requires a ladder or similar means, or from slipping or falling on the wet surfaces in the drum. Injury may also be caused by loosened pieces of concrete which can fall from the upper surfaces in the drum. In addition, it is noisy in the drum during the cleaning operation as a jackhammer, sledge hammer or similar device is typically used to beat the concrete off of the interior surfaces.
Accordingly, the present invention is directed to overcoming the shortcomings of prior art systems.